Art of reclaiming rubber from waste rubber stock



(No Model.)

N. G. MITCHELL. ART OF REGLAIMING RUBBER PROM WASTE RUBBER STOCK. No. 425,896.

Patented Apr. 15,1890.

SYII/III/IIIIIIIIIIIIIII/III/IIA ,1,""11","lununnlum rm: uonms warms cm, Moro-mun. WASHINGTON. u. c.

UNITED ST TES PATENT OFFICE.

NATHANIEL O. MITCHELL, OF PHILADELPHIA, PENNSYLVANIA.

ART OF RECLAIMING RUBBER FROM WASTE RUBBER STOCK.

SPECIFICATION forming part of Letters Patent No. 425,896, dated April 15, 1890.

ApplioatioirfiledFebruary 28, 1890. Serial No. 342,081. (No model.)

T0 aZZ whom it may concern:

Be it known that I, NATHANIEL CHAPMAN MITCHELL, of Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented a new and useful Improvement in the Art of Reclaiming Rubber from YVaste Rubber Stock, which improvement is fully set forth in the following specification.

This invention has reference to the treatment of old rubber stocksuch as boots and shoesfor the purpose of separating foreign matters from the rubber and restoring the latter to a condition suitable for reuse.

In Letters Patent No. 420,820, granted to me February 4:, 1890, Ihave described a method of and apparatus for devulcanizing and desulphurizing waste rubber by the use of live steam under high pressure, the rubber having been dosed with heavy petroleum and calcium sulphide. For various reasons, as set forth in the above patent, a constant current of steam is kept passing through the devulcanizer, the exit-pipe being always open. Of course this operation consumes a great amount of steam, which is one of the large items of expense. Furthermore, in its action upon the contents of the devulcanizer the steam takes up matters which give it a highly offensive odor, on which account it has been found necessary to condense and drain it off.

The object of this invention is to utilize the steam passing from the devulcanizer and to avoid the necessity of condensing the steam. These objects I accomplish by connecting the exit-pipe from the devulcanizer with the cookin g tank or vessel in which the stock is treated to destroy or disintegrate the fiber associated therewith. From this source may be supplied practically all the steam required for the disintegrating process, and experience shows that the sulphur compounds associated with the steam from the devulcanizer have no detrimental effect upon the operation of disintegrating the fiber. As a further result of this improvement the steam in the operations of the cooking-tank is deprived of all noxious odor, so that it can without offense be allowed to escape freely into the atmosphere.

In the accompanying drawing, which forms partof this specification, I have shown in sectional elevation the cooking tank or vessel connected with the exhaust-pipe of the devulcanizer.

, The vessel or tank A may be constructed as described in Letters Patent No. 418,08, granted to me December 24, 1889. It is provided with the steam-inlet pipe B, having a number of branches T), by which the steam is distributed throughout the contents of the vessel.

' 0 represents the devulcanizer, having the steam-inlet pipec and the steam-outlet D, the pipe D being provided with a cook or valve d. The escape-pipe D connects with the inlet-pipe B of the cooking-tank, so that while the operation of devulcanizing a batch of stock from which fibers have been separated by previous treatment is going on in cylinder 0 another batch of stock is treated in tank A for destruction of the fiber by the exhauststeam of the devulcanizer. The steam from the vessel A passes off through a pipe E, by which it may be discharged into the atmosphere.

I claim as my invention- Theimprovement in the art of recovering rubber from old rubber stock, which consists in treating the stock with live steam to devulcanize the same, and then conveying the same steam to the cooking-tank for action upon another batch of stock treated therein for removal of fiber, substantiallyas described.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

NATHANIEL C. MITCHELL.

\Vitnesses:

E. M. MUNDY, C. W. (JRoAsmLL. 

